1. Field of the Invention
The present invention relates to a sanitary napkin comprising: a main body including a liquid absorbent layer; and leakage preventing walls extending longitudinally on a skin-side surface of the main body.
2. Description of the Related Art
In absorbent hygiene products, a main body is typically constructed to include a liquid-permeable topsheet, a liquid-impermeable backsheet and a liquid absorbent layer (absorbent core) disposed between the topsheet and the backsheet. Optionally, leakage preventing walls (cuffs) are disposed on a skin-side surface of the main body so as to prevent lateral leakage of liquid applied to the main body.
The leakage preventing wall is composed of: a sheet which is fixed to the skin-side surface of the main body to have a longitudinally extending base; and elastic members which are fixed to the sheet so as to longitudinally exert an elastic contractive force. With the elastic contractive force being exerted to bring front and rear portions of the main body closer to each other, the skin-side surface of the main body is concavely deformed, resulting in rising of the leakage preventing walls with their free ends moved away from the skin-side surface of the main body.
When employed in disposable diapers, the leakage preventing walls are typically constructed to rise obliquely inward so that the free ends are located closer to a longitudinal centerline of the diaper than the base, as disclosed in Japanese Unexamined Patent Publication No. 2001-293031 (Patent Publication 1) for instance. This is because disposable diapers are intended to receive a large amount of urine, as well as loose passage, at a time. With the leakage preventing wall rising obliquely inward, a pocket is formed between the skin-side surface of the main body and the leakage preventing wall, easily retaining the urine and loose passage. In addition, since the disposable diapers are of a relatively large width, the right and left leakage preventing walls can be located far away from each other. Accordingly, even when the inward leakage preventing walls fall to the skin-side surface of the main body, a relatively large area of the liquid absorbing region can remain exposed between the fallen leakage preventing walls.
On the other hand, sanitary napkins to be worn in the wearer's crotch are of a relatively small width. Accordingly, if the leakage preventing walls are disposed inward as in the diapers and fall to the skin-side surface of the main body due to contact with the crotch, they may extend to adjacent the vaginal opening, reducing the area substantially capable of absorbing liquid in the skin-side surface of the main body.
Consequently, the leakage preventing walls employed in the sanitary napkins are typically constructed to include: a rising portion that is allowed to rise from the skin-side surface of the main body; and a skin-contacting portion that is contiguous to an upper end of the rising portion and has an outwardly directed free end, as disclosed in Japanese Unexamined Patent Publication No. 2001-145667 (Patent Publication 2) and Japanese Unexamined Patent Publication No. 2002-656 (Patent Publication 3). When the sanitary napkins of this type are put on the crotch, the skin-contacting portions come into face-to-face contact with the crotch, thereby improving contact between the leakage preventing walls and the wearer's body. They are also aimed at preventing the area capable of absorbing liquid in the skin-side surface of the main body from being extremely reduced even when the skin-contacting portions fall to the skin-side surface due to contact with the crotch.
FIG. 11 is a schematic diagram showing a state where a conventional sanitary napkin 100 such as disclosed in Patent Publication 2 is put on the wearer's crotch.
The sanitary napkin 100 has a main body that is constructed to include a liquid-permeable topsheet 101, a liquid-impermeable backsheet 102 and a liquid absorbent layer 103 interposed therebetween. Fold-back flaps 104, 104 extend outwardly from transversely opposing sides of the main body. With the fold-back flaps 104, 104 being folded back along both side edges of a crotch part 110 of an undergarment and adhered to an outer surface of the crotch part 110, the sanitary napkin 100 can be positioned on the undergarment.
On right and left portions of the main body of the sanitary napkin 100, there are provided leakage preventing walls 105, 105. When no external force is exerted on the conventional sanitary napkin 100 such as disclosed in Patent Publication 2, skin-contacting portions 105a, 105a of the leakage preventing walls 105, 105 extend generally parallel with the skin-side surface of the main body with their outer edges 105a1, 105a1 directed transversely outward.
FIG. 11 also shows the crotch of a woman, wherein 121 represents the vaginal opening, 122 represents the labia majora, 123 represents the thigh, and 124 represents a narrow depression between the thigh 123 and the abdomen.
When the conventional sanitary napkin 100 comes into contact with the crotch and the thighs 123, 123, the skin-contacting portions 105a, 105a of the leakage preventing walls 105, 105 tend to be deformed with the outer edges 105a1, 105a1 moved downwardly, thereby forming spaces between the skin-contacting portions 105a, 105a and the wearer's body along the depressions 124, 124.
The sanitary napkin 100 is designed to absorb menstrual blood discharged from the vaginal opening 121 in the liquid absorbent layer 103, but when liquid absorbent layer 103 is given too much menstrual blood to absorb, it may flow down the crotch to leak out laterally. If spaces are formed between the skin-contacting portions 105a, 105a and the wearer's body, as set forth above, the menstrual blood flowing down the crotch tends to leak out beyond the skin-contacting portions 105a, 105a and reach the thighs 123, 123, causing the possibility that the undergarment will be stained with menstrual blood.
When the wearer is seated or sleeping, moreover, the menstrual blood having flown down the crotch tends to migrate farther anteriorly or posteriorly along the depressions 124, 124, easily causing rearward leakage of menstrual blood out of the sanitary napkin 100.